In a related-art linear ultrasonic motor, an ultrasonic vibrator having a piezoelectric element fixed thereto is vibrated by applying a high frequency voltage to the piezoelectric element. The vibration of the ultrasonic vibrator drives a sliding member impressed with the ultrasonic vibrator. The linear ultrasonic motor has been variously designed so as to keep a high output with a small size and to enhance drive efficiency.
For example, in a linear ultrasonic motor disclosed in PTL 1, an ultrasonic vibrator having a piezoelectric element is provided with two drivers which are held in abutment against a driven member and four rolling members between the driven member and a base member. The four rolling members are arranged at an interval so that the four rolling members cannot enter between the two drivers in the drive direction of the driven member.